The present invention relates to a MRI system (magnetic resonance imaging system) and a movable table. More particularly, the present invention relates to a MRI system and a movable table capable of properly dealing with joint motion imaging.
A conventional MRI system employs a stationary table integrally combined with a magnetic unit. A specimen, i.e., a patient, is laid down on the stationary table for the production of images of the specimen. The stationary table, however, makes joint motion image production, i.e., kinematic image production, in which images of a joint in different angular positions are produced, difficult.
Accordingly, it is an object of the present invention to provide a MRI system suitable for joint motion imaging.
According to a first aspect of the present invention, a MRI system comprises a vertical magnet means having a pair of vertical magnets having opposite vertical surfaces, and a wheeled movable chair capable of entering a space between the pair of opposite vertical magnets with a specimen seated thereon.
The insertion of the movable chair carrying a specimen seated thereon into a magnetic unit facilitates joint motion image production. However, it is difficult to send the movable chair carrying a specimen seated thereon into the magnet unit of a cylindrical magnet MRI system provided with a cylindrical magnet or a horizontal magnet MRI system provided with a pair of horizontal magnets respectively having opposite horizontal surfaces, because part of the magnet lies between a magnet center, i.e., a position where the intensity of a gradient magnetic field is naught, and the surface of the floor.
The MRI system of the present invention employs a vertical magnet unit having a pair of opposite vertical magnets, and a movable chair capable of entering a space between the pair of opposite vertical magnets. Any part of the magnet does not lie between the magnet center and the surface of the floor in the vertical magnet type MRI system provided with a pair of vertical magnets having opposite vertical surfaces. Therefore, the movable chair carrying a specimen seated thereon can be moved to the magnet center, so that joint motion imaging can properly be achieved.
According to a second aspect of the present invention, the foregoing MRI system further comprises a chair locking means capable of locking the movable chair positioned in the space between the pair of opposite vertical magnets of the vertical magnet means.
The chair locking means may be provided only at the opposite vertical magnet side, only at the movable chair side or at both the opposite vertical magnet side and the movable chair side.
According to a third aspect of the present invention, a MRI system comprises a vertical magnet means having a pair of vertical magnets having opposite vertical surfaces, a wheeled movable table capable of carrying a cradle in which a specimen is laid down into and out from a space between the pair of opposite vertical magnets, a table locking means for locking the table positioned in the space between the pair of opposite vertical magnets of the vertical magnet means, a wheeled movable chair capable of entering a space between the pair of opposite vertical magnets with a specimen seated thereon, and a chair locking means capable of locking the movable chair positioned in the space between the pair of opposite vertical magnets of the vertical magnet means.
Joint motion imaging can satisfactorily be achieved if a specimen held in a sitting position on a chair can be sent into the magnet unit. However, it is difficult to send the specimen held on a chair in a sitting position into the magnet unit of a cylindrical magnet MRI system provided with a cylindrical magnet, or a horizontal magnet MRI system provided with a pair of horizontal magnets respectively having opposite horizontal surfaces, because part of the magnet lies between a magnet center, i.e., a position where the intensity of a gradient magnetic field is naught, and the surface of the floor. In the vertical magnet type MRI system provided with a pair of opposite vertical magnets respectively having opposite vertical surfaces, any part of the magnets does not lie between the magnet center and the surface of the floor. However, a specimen held on a chair in a sitting position cannot be sent into the magnet unit because a stationary table interferes with the chair.
A MRI system of the present invention employs a vertical magnet unit having a pair of opposite vertical magnets, a movable table, and a movable chair.
In a vertical magnet type MRI system, no magnet lies between a magnet center, i.e., a point C in FIG. 2, and the surface of the floor, i.e., a surface F in FIG. 2. The movable table can easily be removed from the magnet unit. Therefore, the movable chair holding a specimen in a sitting position thereon can be moved to the magnet center after removing the movable table from the magnet unit. Thus, joint motion imaging can satisfactorily be achieved.
The table locking means may provided only at the opposite vertical magnet side, only at the movable table side or at both the opposite vertical magnet side and the movable table side. The chair locking means may provided only at the opposite vertical magnet side, only at the movable chair side or at both the opposite vertical magnet side and the movable chair side.
According to a fourth aspect of the present invention, in the MRI system according to any one of the first to the third aspect of the present invention, the movable chair is used for the joint motion imaging of the lumbar region or the neck region.
The medical examination of the lumbar and the cervical vertebrae can satisfactorily be achieved by carrying out joint motion imaging while the lumbar and the cervical vertebrae are moved under load.
According to a fifth aspect of the present invention, a movable table for horizontally moving a cradle in which a specimen is laid down by electric power, comprising wheels, and a power receiving means for receiving electric power for driving the cradle for horizontal movement from a gantry.
Since electric power for driving the cradle for horizontal movement is received from the gantry, the movable table need not be loaded with heavy batteries and can lightly be moved.
Work for laying a patient down on a stationary table in a place in which it is difficult to carry out such work, such as a place where the MRI system is installed, will make the burden too heavy for the patient and the technicians. Since the MRI system cannot be operated during work for laying the patient down on the stationary table, the rate of operation of the MRI system is reduced.
When the MRI system and the movable table of the present invention are used, a specimen laid down on the movable table or the movable chair at some other place can be transported to and can be sent into the magnet unit. Therefore, specimen transferring work is unnecessary, which reduces burden on the patient and the technicians. Since the specimen can quickly be changed, downtime during which the MRI system is stopped can be shortened and the rate of operation of the MRI system is increased.
The MRI system according to the present invention enables the specimen to be carried in a sitting position to the magnet center and is able to deal properly with joint motion imaging.
The movable table according to the present invention receives electric power for driving the cradle for horizontal movement from the gantry. Therefore, the movable table need not be loaded with heavy batteries and can lightly be moved.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.